Ocean Acidification impact on trace elements (by Justine)

The target of the experiment is to study the impact of the acidification on the physical and chemical speciation of the nutrient elements as phosphorus, nitrogen and iron. Since ten days, the typical day at Stareso begins by the sampling inside the nine mesocosmes and outside mesocosms thanks to the cubi platforms. Oooohh the cubi … it’s very funny … and again more with the wind like yesterday and today!! Fortunately, a yoga class have been installed in Stareso (appointment time: 6:00 pm !!) and I’m going to try it !
After sampling, we go to the lab to filter the samples at two different fractions (0.2 µm and 0.015 µm).
Filtration device used in Stareso

After analysis of Dissolved Inorganic Nitrogen (DIN), Dissolved Inorganic Phosphorus (DIP) and Dissolved Iron (DFe) by spectrophotometry at the lab (LOV), in cleaned and controlled conditions, these filtrations will allow us to quantify the nutrient elements on two forms: dissolved (0.015 µm) and colloidal (0.2 µm).

UV irradiation system

With Cecile, we use also the samples filtered at 0.2 µm to determine the organic nitrogen and organic phosphorus. For that, the samples are irradiated by UV during 1h30. We are very impatient to discover the relation between inorganic and organic phosphorus after to have seen the data of alkaline phosphatase of Mauro in the most perturbated mesocosmes (P4-P5-P6).

Other experience: thanks to Alina’s help the microlayer (=thin layer between the ocean and the atmosphere) is taken, and so we have decided to analyze its composition at nutrients on forms inorganic and organic.